Application of High Frequency EPR to Integer Spin Systems: Unusual Behavior of the Double-Quantum Line
A high-frequency EPR study is presented of the integer spin system Ni(II) in the host of Zn-tris(ethylenediamine) dinitrate. This complex shows a broad structureless line at X band. At D band (130 GHz) however, a standard triplet powder spectrum is observed. Superimposed on this spectrum is a "double-quantum" line at the expected position. The microwave power dependency of this line is found to be in contradiction with existing theory on multiple-quantum transitions. The line in our spectra shows a single quantum line behavior in intensity and linewidth as a function of the microwave frequency from 35 to 130 GHz. A literature survey leads to the conclusion that most double-quantum features in high-spin systems do not follow the P3/2 power dependency predicted by second-order perturbation theory. In our case the double-quantum line is assigned to an enhancement effect due to the simultaneous excitation of two single-quantum transitions. Copyright 1998 Academic Press. Copyright 1998 Academic Press
van Dam PJ
Department of Molecular Spectroscopy, University of Nijmegen, Toernooiveld 1, Nijmegen, 6525 ED, The Netherlands
Klaassen
AAK
Reijerse
EJ
Hagen
WR